Electronic components and chips are tested during production or following production. Automatic test apparatuses (automatic test equipment, ATE) may be used, for example, to subject chips or electronic components to marginal tests, parameter tests or functional tests.
In order to test the function of differential integrated circuits, a symmetrical (differential) test input signal is generally needed to test the error-free function of the circuit. Particularly in the case of circuits for the extra-high frequency range above approximately 20 GHz, the problem arises in this case that it is technically difficult to generate corresponding differential test signals on account of the very short wavelengths in the millimeter range since the requisite phase difference of 180 degrees often cannot be ensured on account of mechanical tolerances and production tolerances. In addition, corresponding devices such as frequency generators with a symmetrical output are very expensive. Therefore, the testing of extra-high frequency circuits with a differential input is problematic, which is additionally due to the lack of availability of corresponding measurement technology such as differential measuring tips for the frequency range above approximately 20 GHz.
On account of the abovementioned difficulties, such extra-high frequency circuits are often tested using alternative methods, for instance by measuring DC and low-frequency properties. Some of these results are additionally correlated with data obtained from monitoring the production process (Process Control Monitoring—PCM). However, the actual function of the components is not measured during such methods or similar methods. Therefore, they generally result in higher rates of undetected errors than tests which relate to the function of the components under relatively practical conditions.